For years, electronic packaging has centered around Dual Inline Packaging (DIP) and Flat Pack component construction techniques, with discrete components, hybrids, or special packages using cans or potted molds meeting various packaging requirements. These devices were mounted on printed circuit (PC) boards, which served to electrically interconnect the circuitry to perform various electronic functions.
On PC boards, DIP components may be wired by placing component leads, or component carrier leads through holes in the PC board and flow soldering the board using automatic machinary. This type of construction is often preferred over Flat Pack techniques because Flat Packs lay on the board and can not easily be wavesoldered. Automatic bonding of Flat Packs to PC boards, however, may be realized with induction heaters and hot vapor heating techniques. In addition DIP construction is preferred because Flat Packs have leads that extend outward from the body and require more PC board real estate than DIP components. The more components and circuits that can be placed on a single board, the fewer boards required for an electronic device, and the less expensive the device. Applications for both types of packages still exist and component manufacturers make components in both Flat Pack and DIP configurations.
More recently, a newer technique called Surface Mounted Technology (SMT) has evolved. Components for this technology are usually very small and have solderable pads instead of leads. These components mount on the boards with off shoots of the solderable pads overlapping pads on the PC board and are soldered to the PC board with solder paste, or with the soldering technology developed for Flat Pack attachment. Automatic construction techniques have been conceived for each of the above processes, wherein individual components are mounted on rolls or in stacks and dropped into position on the boards for permanent soldering. These automatic constructions also pretin the leads, apply solder or solder paste, reflow solder, wave solder, hot fluid solder, apply flux, clean the boards, etc.
As PC boards became more sophisticated, with more conductive layers and ground planes, methods of through hole plating to electrically interconnect various layers of the boards, and to join leads coming through the boards, were developed. U.S. Pat. No. 4,322,778 issued to Barbour et. at. entitled "High Performance Semiconductor Package Assembly" describes a semiconductor package with a plurality of integrated circuit devices having a multilayer substrate. U.S. Pat. No. 4,368,503 issued to Kurosawa et. al. and U.S. Pat. No. 4,389,278 issued to Kai describe different methods of interjoining multilayers and fabricating such boards.
U.S. Pat. Nos. 4,109,295 and 4,109,296 both issued to Rostek, et. al. describe a circuit board component which is mounted by inserting the component into a hole in the circuit board. This component has one or more conductive sectors around its periphery to attach, either by solderable or gas tight means, to a similar number of conductive sectors about the hole wherein the component is inserted for mounting on the board.
It is evident that a most desirable electronic circuit package is one that is easily manufactured at low cost with automatic equipment, is configured for reel, roll or stack mounting in automatic machinary, is easily held and easily keyed for accurate positioning on PC boards, has accessible leads, is not easily bent or misconfigured, and is mountable in either through hole DIP, Flat Pack or SMT boards.
It is further evident that this desirable component configuration should require minimum PC board real estate and a minimum number of drilled holes for a DIP board construction (since drilling holes is time consuming and costly).
It is further evident that this desirable package lends itself to sizing in various compatible dimensions for different types of component and/or chips, for operation over a broad range of signal and power levels, and to standardization in a family of components to permit close mounting and the sharing of heat removal devices.
It is further evident that this desirable component configuration offers "hybrid" features to share DIP, Flat Pack, or SMT leads.
It is further evident that this desirable package unites many conductive leads in a single form to make a rigid structure, thereby providing greater lead integrity than packages with fine conductive leads projecting from a chip housing.